At a joint news conference of US and South Korean defence and foreign ministers in Washington on Thursday, Clinton said North Korea leader Kim Jong-Un had a chance to "chart a different course for his people".

The North Korean foreign ministry spokesman said: "...how foolish and ridiculous the US was in its attempt to meddle in the internal affairs of the DPRK (North Korea) over its 'human rights issue' and 'people's living' and hurt its single-minded unity.

"Hillary would be well advised to pay more attention to the issues of economic crisis and huge hordes of jobless people, which have become so serious that they may dash the hope of the administration of the Democratic Party for stay in power."

The official also said North Korea would make "sustained efforts to bolster up its nuclear deterrent to guarantee the peace and security of the country and the nation as long as the US persistently antagonises it".

Clinton had said there must be change in communist North Korea, "Because at some point people cannot live under such oppressive conditions, starving to death, being put into gulags and having their basic human rights denied."